去除轻组有机质对湖泊沉积物磷释放速率的影响研究

Effects of Light Fraction Organic Matter Removal on Phosphorus Release from Lake Sediment

采用重液（NaI）分离法去除了贡湖、五里湖和月湖沉积物中的轻组有机质（LF），研究了LF去除对沉积物磷释放动力学曲线的影响．结果表明，沉积物LF的去除并没有影响溶解性磷酸盐（SRP）和溶解性有机磷（DOP）释放动力学曲线的基本趋势，在前12h内，沉积物中磷的释放具有较大速率，12h后基本达到平衡．去除LF前后湖泊沉积物释放动力学均符合抛物线扩散方程（P〈0．001）；LF去除提高了各沉积物磷的释放量、释放速率，特别是提高了0～1／12h内的释放速率，其中SRP释放速率增加了8．09～24．2倍，DOP增加了1．15～2．01倍；去LF后，提高了沉积物的pH，促进了磷的释放．主要是通过OH^-对沉积物铁／铝结合态磷的阴离子置换和破坏了轻组有机质的羧基（-COOH）及羟基（-OH）和沉积物中的无机物胶体形成的胶结物．沉积物磷的释放与有机质的氨基、羧基、羟基等官能团有关．

Effect of light fraction organic matter （LF） removal on phosphorus （P） release from lake sediments was studied. LF of the different trophic sediments from the Yuehu Lake, Wuli Lake and Gonghu Lake were removed by physical density （NaI） separation. The removal of LF shows a little effect on the P release kinetics from lake sediments. Within the first 12 hours, the release rates of soluble reactive phosphorus （SRP） and dissolved organic phospho- rus （DOP） is higher than other time, and then tends to an equilibrium state. The data of P release rates fitted to the parabolic diffusion equation （P〈0. 001）. The removal of LF increases the amount of the P released and its release rate, espec hours. The release rate of SRP increases from 8.09 to 24. ially for its release rate within 1/12 imes, and DOP from 1.15 to 2.01 times. The removing of LF from the sediments accelerated the P release mainly relate to the two reasons. One is to replace phosphate ion existing in a form of Fe/Al-bounded phosphorus in the sediment with OH^- through enhance pH, and the other is to destroyed colloid of LF with sediment of the carboxyl group （-COOH） and hydroxyl （-OH）. So the processes of P release from lake sediment relates to its amido, carboxyl, and hydroxide of organic matter.